Shukee Begum, 33, travelled to Syria with her children to find her husband Jamal al-Harith, a former Guantanamo Bay detainee who left Britain 18 months ago to join the group, Channel 4 news reported.

A law graduate from northern England, Begum insists she only travelled to convince her husband to return and never supported the IS militants, who have carved out regions of control in Iraq and Syria.

"I was seeing on the news at this point that ISIS was going from bad to worse... So I decided that I was going to try and speak some sense into him," she told Channel 4 news, referring to Islamic State by an alternative name.

At first, Begum lived in a overcrowded safe house in the IS-controlled city of Raqqa with dozens of other women and children, many "crying" and "sick".

"There was a gangster kind of mentality among single women there. Violent talk, talking about war, killing," Begum said.

"They would sit together and huddle around their laptops and watch ISIS videos together and discuss them and everything. It was just not my cup of tea."

After she was reunited with her husband, who refused to help her leave, IS authorities would not allow her to go, Begum added.

"This is what I want to make clear as well to other women thinking of coming into ISIS territory -- that you can't just expect to come into ISIS territory and then expect that you can just leave again easily," Begum said.

"There is no personal autonomy there at all."

She was smuggled out of the territory before being held captive in the city of Aleppo, and is now living close to the border with Turkey and hopes to move back to Britain, Channel 4 reported.

Hundreds of Britons are thought to have travelled to join the IS group.

A report released last month indicated that dozens of fighters have defected from the group, which has become notorious for beheadings and blowing up ancient Syrian monuments, often due to disillusionment over killing fellow Sunni Muslims and civilians.